1. Field of the Invention
The present general inventive concept relates to an audio apparatus, and more particularly, to an apparatus and method of generating multi-channel audio signals.
2. Description of the Related Art
Multi-channel audio systems have become a standard for movies and home theaters and have been used in audio applications such as music, cars, and computers. In addition, the multi-channel audio systems are also considered to be used in television broadcasting. The multi-channel audio systems provide a surround sound environment to enhance a listening quality and overall presentation of an audio-visual system. Conventional stereo systems have been replaced with the multi-channel audio system due to various factors. One of the most important factors is consumer's demand for high quality audio. For the high quality audio, audio systems having more channels, hi-fi channels, and enhanced channel separation are needed. To meet the demand, 2-channel audio signals need to be converted into signals which are optimized for the multi-channel audio system such as 4-channel, 4.1-channel, and 5.1-channel audio systems.
FIG. 1 is a block diagram illustrating a conventional multi-channel audio signal generation apparatus for converting 2-channel audio signals into 4-channel audio signals.
A correlation measurement unit 100 calculates signals L−R and L+R based on input sources L and R and generates a surround-channel signal S and a center-channel signal C using the signals L−R and L+R. In addition, the correlation measurement unit 100 measures a correlation between the surround-channel signal S and the center-channel signal C. Then, the correlation measurement unit 100 generates control voltages according to the measured correlation and applies the control voltages to a matrix generation unit 110.
The matrix generation unit 110 generates a matrix which minimizes interferences of the signals using the input sources L and R and the control voltages generated by the correlation measurement unit 100.
A channel generation unit 120 generates a left-channel signal LEFT, a right-channel signal RIGHT, a center-channel signal CENTER, and a surround-channel signal SURROUND using the matrix generated by the matrix generation unit 110.
However, conventional multi-channel audio signal generation apparatuses require complex calculations such as correlation measurement and matrix generation and have problems of unreliable channel separation for signals which are not optimally encoded for the conventional multi-channel audio signal generation apparatuses, and generation of an signal excessively concentrated to a center-channel for a signal which is close to a mono-type signal.